1. Technical Field of the Invention
The present invention relates to the field of signal processing, and pertains in particular to a preprocessing performed at the input of a digital device.
The invention pertains more particularly to the processing of radiofrequency signals implemented in a digital processing device for signals such as a device known by the term of art as a “software radio”.
2. Description of Related Art
A software radio is a device for processing a radiofrequency signal of purely digital nature.
The realization of such a device makes it necessary to process a bandwidth at least equal to twice the clock frequency. To process the incoming signal in real time and in a synchronous manner, the clock frequency to be considered is in relationship with the frequency of the radiofrequency domain, i.e. generally 2 GHz. The bandwidth of the signal digital processing device must therefore be equal to at least 10 GHz.
Additionally, the power gap of the signal arriving at a radiofrequency antenna may lie between a minimum of −100 dbm and a maximum of −20 dbm. The amplitude of the signal received may therefore be of the order of 100 db. It is then necessary to use a sampling with at least 16 bits to digitize signals of such an amplitude.
The constraints applying to the bandwidth and to the amplitude of the signal require considerable calculation power. The power consumption of calculation devices capable of carrying out such calculations is conventionally of the order of 500 to 1000 watts. Such power consumption is incompatible with the portability requirements of a software radio.
It is therefore desirable to decrease the complexity of the calculations to be carried out for processing signals arising from a radiofrequency antenna.
It is also necessary to decrease, in the same manner, the power consumption of the calculation means implemented for processing the radiofrequency signals.
Applicants further reference and incorporate by reference herein French Application for Patent No. 07 55441 entitled “Method and Electronic Device for Frequency Shifting an Analog Signal, in Particular for Mobile Telephony” by Didier Belot, et al. filed Jun. 4, 2007 and filed as PCT/FR2008/50973 on Jun. 3, 2008 (also incorporated herein by reference).